B

Now satellites are helping to forecast(预报) the weather. They are in space, and they can reach any part of the world. The satellites take pictures of the atmosphere(大气) , because this is where the weather forms(形成).They send these pictures to the weather stations. So meteorologists(气象学家) can see the weather of any part of the world. From the pictures, the scientists can often say how the weather will change.

Today, hundreds of weather stations in sixty countries receive satellite pictures. When they receive new pictures, the meteorologists compare them with earlier ones. Perhaps they may find that the clouds have changed during the last few hours. This may mean that the weather on the ground may soon change, too. In their next weather forecast, the meteorologists can say this.

So the weather satellites are a great help to the meteorologists. Before satellites were invented, the scientists could forecast the weather for about 24 or 48 hours. Now they can make good forecasts for three or five days. Soon, perhaps, they may be able to forecast the weather for a week or more ahead(提前).

41. Satellites travel _____ .

A. in space        B. above space

C. above the ground      D. in the atmosphere

42.Why do we use the weather satellites to take pictures of the atmosphere?

A. Because clouds form there.

B. Because the weather forms there.

C. Because the weather satellites can do it easily.

D. Because the pictures can forecast the weather.

43. Meteorologists forecast the weather            .

A. without studying satellite pictures

B. before they receive satellite pictures

C. when they have received satellite pictures

D. after they have compared the new satellite pictures with the earlier ones

44. Maybe we’ll soon be able to forecast the weather for   _____

A. one day        B. two days

C. five days       D. seven days or even longer

45. The main idea of this passage is that satellites are now used in    _____     .

A. taking pictures of the earth    B. receiving pictures of the atmosphere

C. weather forecasting     D. doing other work in many ways